I don't believe black midi can be played on normal instruments, it's mostly computer-based (barring the punchcard pianos). In fact even standard pre-black-midi software would probably crash when trying to open such files.
I have a real piano capable of midi input here and there is no way I'm going to test the power supply and solenoid drivers by sending them that kind of data because I'm pretty sure that the designers did not anticipate this kind of use.
A piano has only 88 keys (if you play outside of those it doesn't sound like a piano anymore, even on a computer). And if you use more than one piano at the same time, all what happens is a phasing effect if more than one hits the same note at the "same" time.
The point is that if the MIDI file and the synthesiser in question are all on the same system (i.e. a VST in a DAW), no MIDI data transfer has to take place. So the data transfer limit in question isn't applicable.
Even if it's on the same system your piano still has 88 keys and you get either a loudness gain per key or a phasing effect when a key is played more than once per time. The only somewhat interesting effect (at least for some) might be that the generator hits its limits (usually 20 to 40 notes polyphony) and randomly decides which notes to leave out or prioritize. But this is out of control of the "composer" and likely not the intended effect.
